[coreboot] GPIOs on CS5536 based boards

Peter Stuge peter at stuge.se
Wed Sep 23 17:52:35 CEST 2009

Daniel Mack wrote:
> Also, when booting Linux, the LED driver does not work with
> coreboot for me.

The issue is that the driver is using a hard coded base address
rather than finding out what is actually programmed into the device,
and because coreboot doesn't assign resources exactly like the
factory BIOS, the driver can't find the hardware.

The driver should be improved to read the base address from the MSR,
then it would work everywhere.

Another sad fact is that the driver scans the BIOS 0xf0000 segment
for a particular string which is present in the factory BIOS, but not
in coreboot. I believe there is an override.

You may find msrtool helpful since it knows a bit about Geode,
although not nearly everything. It's good with the DIVIL and

boot factory BIOS
# msrtool -l -s file
this saves a list of known MSRs along with their values into file

boot coreboot
# msrtool -d file
this shows decoded MSR differences between saved and current values


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